Table 3.
Post-vaccination poliovirus SNA responses and median antibody titres in those aged 24–59 months
| Needle and syringe (n=582) | Disposable syringe jet injector (n=574) | Intradermal adapter (n=527) | Total (n=1683) | |
|---|---|---|---|---|
| Poliovirus type 1 | ||||
| Seroprevalence | 578 | 570 | 521 | 1669 |
| Seroprevalence % | 99·3% (98·1–99·6) | 99·3% (98·1–99·6) | 98·9% (97·5–99·5) | 99·2% (98·5–99·5) |
| Median antibody titres | ≥1448 (1448–1448) | ≥1448 (1448–1448) | ≥1448 (1448–1448) | ≥1448 (1448–1448) |
| Seroconversion | 29/32 | 28/32 | 34/39 | 91/103 |
| Seroconversion % | 90·6% (75·8–96·8) | 87·5% (71·9–95·0) | 87·2% (73·3–94·4) | 88·3% (80·6–93·1) |
| Four-fold titre rise | 280/288 | 240/256 | 250/260 | 770/804 |
| Four-fold titre rise % | 97·2% (94·5–98·5) | 93·8% (90·0–96·0) | 96·2% (93·0–97·9) | 95·8% (94·0–97·0) |
| Immune response | 309/320 | 268/288 | 284/299 | 861/907 |
| Immune response % | 96·6% (94·0–98·0) | 93·1% (89·5–95·5) | 95·0% (91·9–96·9) | 94·9% (93·3–96·1) |
| Poliovirus type 2 | ||||
| Seroprevalence | 582/582 | 574/574 | 527/527 | 1683/1683 |
| Seroprevalence % | 100·0% (99·3–100·0) | 100·0% (99·3–100·0) | 100·0% (99·3–100·0) | 100·0% (99·8–100·0) |
| Median antibody titres | ≥1448 (1448–1448) | ≥1448 (1448–1448) | ≥1448 (1448–1448) | ≥1448 (1448–1448) |
| Seroconversion | 15/15 | 21/21 | 17/17 | 53/53 |
| Seroconversion % | 100·0% (79·5–100·0) | 100·0% (84·5–100·0) | 100·0% (81·5–100·0) | 100·0% (93·1–100·0) |
| Four-fold titre rise | 316/338 | 260/291 | 299/310 | 875/939 |
| Four-fold titre rise % | 93·5% (90·3–95·6) | 89·3% (85·3–92·4) | 96·5% (93·8–98·0) | 93·2% (91·4–94·5) |
| Immune response | 331/353 | 281/312 | 316/327 | 928/992 |
| Immune response % | 93·8% (90·6–95·8) | 90·1% (86·1–92·9) | 96·6% (94·0–98·0) | 93·5% (91·8–94·9) |
| Poliovirus type 3 | ||||
| Seroprevalence | 574/582 | 560/574 | 499/527 | 1633/1683 |
| Seroprevalence % | 98·6% (97·3–99·3) | 97·6% (95·9–98·5) | 94·7% (92·4–96·3) | 97·0% (96·0–97·6) |
| Median antibody titres | ≥1448 (1448–1448) | ≥1448 (1448–1448) | ≥1448 (1448–1448) | ≥1448 (1448–1448) |
| Seroconversion | 54/62 | 75/89 | 70/92 | 199/243 |
| Seroconversion % | 87·1% (76·5–93·3) | 84·3% (75·3–90·4) | 76·1% (66·4–83·5) | 81·9% (76·5–86·1) |
| Four-fold titre rise | 365/371 | 339/359 | 305/319 | 1009/1049 |
| Four-fold titre rise % | 98·4% (96·5–99·3) | 94·4% (91·5–96·4) | 95·6% (92·8–97·4) | 96·2% (94·8–97·1) |
| Immune response | 419/433 | 414/448 | 375/411 | 1208/1292 |
| Immune response % | 96·8% (94·5–98·0) | 92·4% (89·5–94·5) | 91·2% (88·0–93·5) | 93·5% (92·0–94·6) |
Data presented as n/N, % (95% CI), or median (95% CI). Seroprevalence is defined as the number of participants with an SNA titre of ≥8 as a proportion of all participants tested. The percentage of children who had an immune response after intradermal fractional dose inactivated poliovirus vaccine was calculated combining the percentage who underwent seroconversion (baseline SNA titres of <8 and a post-vaccination titre of ≥8) with the percentage who were seropositive (SNA ≥8) at baseline and had a four-fold rise in SNA titres post-vaccination. Children with a baseline titre of >362 were excluded from the analysis as a four-fold rise was beyond the upper limit of quantification the assay. SNA=serum neutralising antibody.